Research on the isolation and structure determination of several unknown, biologically active natural products is proposed. All of the structures would be unequivocally established by X-ray diffraction. Compounds from marine organisms, higher plants and microorganisms will be examined. Some specific targets are: 1. K112, K203 and K205, uncharacterized compounds with potential as chemotherapeutic agents in cancer treatment, 2. leucogenenol, a mammalian compound that stimulates wide spectrum myeloid differentiation from bone marrow precursors, and is capable of completing the peripheral T-cell differentiation cycles in the absence of the target thymus organ, 3. ciguatoxin, brevetoxin A and another, unnamed dinoflagellate toxin which appear to be highly unusual polyethers, 4. small antibiotic molecules from Tubastria spp., Uvaria spp. and Pseudopterogorgia bipinnata, 5. the bisintercalating antitumor antibiotic BBM-928A and its interactions with nucleic acids.